Fuel evaporative loss control system with accumulator

ABSTRACT

A fuel evaporative loss control system in which fuel is drained from the carburetor fuel bowl of the carburetor of an internal combustion engine into an accumulator when the engine is not in operation, the fuel thus drained into the accumulator being returned to the fuel bowl upon resumption of engine operation by fuel pump pressure.

O Unite States Patent [72] Inventors Earl W. Ruhr-bachely; Donald B. Elfes, Royal Oak, both of, Mich. 21 Appl. No. 14,270 [22] Filed Feb. 26, 1970 [45] Patented Aug. 24, 1971 [73] Assignee General Motors Corporation Detroit, Mich.

[54] FUEL EVAPORATIVE LOSS CONTROL SYSTEM WITH ACCUMULATOR 8 Claims, 2 Drawing Figs.

52 [1.8. Ci 123/136, 123/139, 123/198 DB [51] Int. c1. ..F02m 37/10 [50] Field ofSearch 123/136,

198 DE, 97 B, 139

[56] Refer-cues Cited UNITED STATES PATENTS 2,986,133 5/1961 Mattson 123/136 3,048,157 8/1962 Gregory et a1. 123/136 3,256,870 6/1966 Walker 123/136 3,534,721 10/1970 King 123/136 Primary Examiner-Mark M. Newman Assistant Examiner-Cort R. Flint Attorneys-Jean 1... Carpenter and Arthur N. Krein ABSTRACT: A fuel evaporative loss control system in which fuel is drained from the carburetor fuel bowl of the carburetor of an internal combustion engine into an accumulator when the engine is not in operation, the fuel thus drained into the accumulator being returned to the fuel bowl upon resumption of engine operation by fuel pump pressure.

This invention relates to a fuel evaporative loss control system for an internal combustion engine and, more particularly, to a system in which an accumulator is used for fuel bowl draining and in which fuel pump pressure is used to effect operation of the accumulator to return stored fuel to the carburetor fuel bowl.

It is well known that vapors and gases emitted from internal combustion engines contribute to the present day problem of air pollution. Accordingly, much attention has been directed to controlling the polluting emissions from internal combustion engines. Many corrective devices have been proposed and utilized to control the most obvious sources of emission, that is, the emission of fumes from the exhaust system and crankcase of the engine.

However, another source of hydrocarbon emissions from an internal combustion engine is the fuel vapor escaping from the fuel system of the engine. In particular, evaporated fuel may escape from the external vents of both the fuel tank and the carburetor float bowl, either while driving or while at rest. A great deal of this evaporated fuel loss originates from the carburetor of the engine. One of the major sources of these carburetor evaporation losses is from the carburetor float bowl, which is a vented reservoir for volatile fuel that is exposed to heat from both the atmosphere and from the engine. These evaporative losses of fuel from the float bowl are essentially the function of fuel volatility, float bowl temperature and carburetor design. The greatest evaporative loss from the carburetor float bowl occurs under hot soak conditions. Hot soak is the condition which occurs after a warmed-up car is stopped and the engine 'turned off, bringing about high-underhood temperatures and substantial losses of hydrocarbon from the carburetor float bowl. This evaporative loss during the hot soak condition can account for from to percent of the fuel remaining in the float bowl at the time the engine is i stopped.

It is, therefore, the principal object of this invention to improve a fuel evaporative loss control system for an internal combustion engine whereby fuel is drained from the carburetor fuel bowl into an accumulator when the engine is not in operation, the fuel being returned to the fuel bowl upon resumption of engine operation by fuel pressure from the fuel system of the engine, thereby preventing evaporative loss of fuel when the engine is not in operation.

Another object of this invention is to provide an improved accumulator for use in a fuel evaporative loss control system of an internal combustion engine for draining fuel from the carburetor float bowl when the engine is not in operation and to return this fuel to the carburetor float bowl upon resumption of engine operation without contamination of the fuel.

These and other objects of the system are obtained by means of a fuel evaporative loss control system in which an accumulator having a roll diaphragm therein provides a fuel storage chamber into which fuel from the carburetor float bowl, wells and accelerating pump of a carburetor is drained when the engine is not in operation and, an actuating chamber into which the fuel pump of the fuel system delivers fuel under pressure to actuate the diaphragm to force fuel from the fuel storage chamber back into the carburetor float bowl upon resumption of engine operation.

For a better understanding of the invention as well as other objects and further features thereof, reference is had to the following detailed description of the invention to be read in connection with the accompanying drawings, wherein:

FIG. 1 is a schematic illustration of a fuel evaporative loss control system for an internal combustion engine having an accumulator in accordance with the invention, the system being shown with the engine in operation; and,

FIG. 2 is an enlarged sectional view of the accumulator of FIG. 1 in fuel storage condition.

0 from the fuel tank. The filler and vent cap 14, illustrated sche- Referring now to FIG. 1, the fuel system for an internal combustion engine utilizing the fuel evaporative loss control system of the invention is illustrated. As shown, a supply of fuel, such as gasoline, for the engine not shown, is contained in a fuel reservoir or tank 10 from which liquid fuel is delivered through a conduit 11 to the inlet of a fuel pump, generally designated 12. The fuel tank 10, provided with a filler neck 13, is closed by a filler and vent cap 14 to control emission matically, incorporates a two-way valve which admits outside air into the tank as fuel is drawn out but will not release fuel vapors to the atmosphere unless a predetermined pressure is reached, whereupon the valve will open to relieve the pressure and prevent rupture of the fuel tank.

The fuel pump 12 can conveniently be of any suitable type but, as schematically illustrated in FIG. 1, is a conventional nonpositive diaphragm-type fuel pump actuated by a pump lever and rocker arm assembly 15 upon rotation of an eccentric 16 on the cam shaft 17 of the engine, not shown. Fuel is drawn into the pumping chamber of the fuel pump via an inlet valve 18 having a bleed orifice therein, not shown, from the conduit 11 connected to the fuel tank 10 and discharged through a discharge valve 19 having a bleed orifice, not shown, into conduit 21 for discharge through a flow control valve 22 into the fuel reservoir or float bowl 23 of a carburetor, not shown, as controlled by a conventional float 24 and needle valve 25 arrangement. The carburetor float bowl is provided with a vent 26 at the top of the bowl open to the atmosphere or, preferably to the carburetor air horn, not shown. The bleed orifices in the inlet valve 18 anddischarge valve 19 are small diameter passages through the valve seats of these valves to permit adequate leakage of fuel back to the fuel tank when the fuel pump is not in operation.

The system of fuel tank, fuel pump and float bowl, thus far described, is foundin a conventional carburetor fuel supply system for an internal combustion engine. To convert the above to a fuel evaporative loss control system, in accordance with the invention, a fuel storage and return system is provided in the form of a conduit 27 in communication at one end with an opening in the bottom of the fuel bowl and in communication at its other end with the fuel storage chamber of an accumulator, generally designated 40, while the fuel pump is connected by conduits 21 and 30 to the actuating chamber of the accumulator.

As described in greater detail hereinafter, the fuel evaporative loss control system of the invention functions in such a manner that upon stopping of the engine, the fuel in the carburetor bowl will be drained and stored in a closed container, that is, the fuel storage chamber of the accumulator until such time as a restart of the engine is initiated. Upon restarting, fuel pump pressure is imposed on the actuating chamber of the accumulator causing sufficient displacement of the diaphragm forming part of the fuel storage chamber to'return all of the previously stored fuel back to the carburetor float bowl.

Referring now to the embodiment of the accumulator 40, shown in detail in FIG. 2, it is in the form of a pressure-volume transformer and includes an upper cap 41, upper body 42, lower body 43 and lower cap 44, which together make up a casing divided into six chambers by flexible diaphragms 45, 46 and 47 sealingly clamped at their outer peripheries between upper cap 41 and upper body 42; between upper body 42 and lower body 43, and between lower body 43 and lower cap 44, respectively. The chambers thus formed are an upper control chamber 50 and lower control chamber 51 on opposite sides of diaphragm 45, a fuel storage chamber 52 and upper null chamber 53 on opposite sides of diaphragm 46 and a lower null chamber 54 and an actuating chamber 55 on opposite sides of diaphragm 47.

Upper body 42 is provided with a through counterbored opening 56 in which is secured a valve assembly consisting of retainer 57, valve seat 58, valve 59 and spring 61 which normally biases the valve 59 against the valve seat 58 to block communication between the lower control chamber 51 and the fuel storage chamber 52. The force of spring 61 is such that the weight of fuel in conduit 27 and in the lower control chamber 51 and the slight suction created as diaphragm 46 is moved from the position shown in FIG. 1 to the position shown in FIG. 2, as described hereinafter, will effect unseating of valve 59 to allow the fuel to drain down into the fuel storage chamber 52 under the operating conditions as described in detail hereinafter.

Valve 59 can also be unseated by means of plunger 62 which is secured to diaphragm 45 for movement therewith. As shown, diaphragm 45 is provided with a central aperture and is clamped between two retainer plates 63 held in position between the shoulder of the plunger 62 and its staked-over upper end. The diaphragm 45 is normally biased upward to position the plunger out of contact with the valve 59 by a spring 64 which encircles plunger 62 with one end of the spring in contact with the bottom retainer 63 and the other end engaging a spring retainer 65 positioned over a stepped bushing 66 mounted in opening 56 and supported on the top of the valve seat 58 in alignment therewith.

Lower body 43 is formed at the bottom therewith with an inverted cup-shaped portion bored in the center to slideably receive piston connecting rod 67 which is recessed at each end to in turn support an upper piston 68 and lower piston 69 at opposite ends thereof.

Diaphragm 46, a roll diaphragm, is secured to the head of the upper piston 68 by means of retainer 71, secured as by staked-over pins 72, with the diaphragm sandwiched between the head of the upper piston 68 and retainer 71. The diaphragm 46 and therefore, the upper piston 68, together with the lower piston 69 which has the diaphragm 47, a roll diaphragm, suitably secured to the head thereof are normally biased downward to the position shown in FIG. 2 by spring 73 which has one end in engagement with the retainer 71 and its other end in engagement with a counterbored seat in body 42.

Thus, diaphragm 46 together with upper piston 68 and diaphragm 47 together with lower piston 69 form the moving walls of the upper null chamber 53 and lower null chamber 54, respectively. The upper null chamber 53 is in direct communication with lower null chamber 54 by means of aperture 74 in the end wall of the cup-shaped portion of lower body 43 and with the atmosphere by means of aperture 75 in the outer lower wall of lower body 43.

' To effect actuation of diaphragm 47 to move the piston assembly upward from the position shown in FIG. 2 to that shown in FIG. 1, fuel under pressure from fuel pump 12 is delivered via conduit 30 to the threaded passage 81 in lower cap 44 in communication with the actuating chamber 55. Downward movement of diaphragm 45 from the position shown in FIG. 2 to the position shown in FIG. 1 is also accomplished by delivery of fuel under pressure from the fuel pump 12 into chamber 50, which in the embodiment illustrated is in communication with actuating chamber 55 via conduit 82 in the upper cap 41, conduit 83 in body 42, tube 84 and conduit 85 in the lower cap 44.

Under engine operating conditions, the system is as shown in FIG. 1, with the fuel pump 12 delivering fuel from the fuel tank under pressure into conduit 21 to maintain a quantity of fuel in the carburetor float bowl 23 at a level as determined by the float valve arrangement therein. Fuel under pressure is also delivered via conduit 30 to the accumulator 40 whereby the fuel under pressure in the actuating chamber 55 retains the diaphragm 47 in the position as shown with the diaphragm 46 moved upward to the position shown against the biasing action of spring 73. In addition, fuel under pressure in the upper chamber 50 forces the diaphragm 45 downward to the position shown in the same figure forcing plunger 62 down to unseat valve 59.

When operation of the engine is discontinued, operation of the fuel pump 12 is discontinued at which time fuel from the conduits 30 and 21 can bleed through the bleed orifice in discharge valve 19 back into the pump chamber and then through the bleed orifice in inlet valve 18 via conduit 11 back into the fuel tank 10. As the pressure of the fuel in conduits 21 and 30 decreases sufficiently, spring 73 will force diaphragms 46 and 47 downward to the position shown in FIG. 2 with the downward movement of diaphragm 46 increasing the volume of the fuel storage chamber 52, thus permitting fuel from the carburetor float bowl to drain via conduit 27 into chamber 51 and then through the unseated valve 59, which is unseated due to the slight decrease in pressure in fuel storage chamber 52 and the weight of fuel thereon, into the fuel storage chamber 52. When the fuel from the float bowl 23 and conduit 27 and chamber 51 has drained completely into the fuel storage chamber 52, which is of a size to accommodate this quantity of fuel, spring 61 will again force valve 59 against the valve seat 58, thus sealing off the fuel storage chamber 52 from the atmosphere. With the fuel thus removed from the float bowl into the fuel storage chamber 52, emission of fuel .vapor from the float bowl after engine shutoff is prevented. The internal parts of the accumulator are then in the positions as shown in FIG. 2.

When operation of the engine is again initiated, fuel is immediately delivered under pressure from the fuel pump 12 into conduits 21 and 30. Since valve 22 in the bottom of the float bowl is a flow control valve set to open at a predetermined pressure, the initial volume of fuel under pressure pumped by the fuel pump will be delivered into the actuating chamber 55 of the accumulator and into the upper control chamber of the accumulator. As this occurs, diaphragm 45 is moved downward against the biasing action of spring 64, with the chamber 51 being in effect in communication with the atmosphere via vent 26 of the float bowl, causing the plunger 62 to unseat valve 59 thereby placing chamber 51 in communication with the fuel storage chamber 52. At the same time, fuel under pressure in actuating chamber is acting against diaphragm 47 to move the diaphragm 47 and the lower piston 59 upward, thus moving the upper piston 68 and diaphragm 46 upward against the biasing action of spring 73 to force the stored fuel in the fuel storage chamber 52 past unseated valve 59 into chamber 51 and then via conduit 27 into the float bowl 23 with the internal parts of the accumulator again in the positions shown in FIG 1.'

Using normal fuel pump delivery with the accumulator shown, the fuel in the fuel storage chamber 52 can be delivered back into the carburetor bowl 23 with as little as two strokes of the diaphragm-type fuel pump 12. If an electrical fuel pump was used in lieu of the fuel pump shown, it would further speed up delivery of stored fuel back to the float bowl since its operation would start immediately when the ignition is turned on and independently of engine operation. However, regardless of the type fuel used, it is preferred that the actuating chamber 55, although inversely variable in volume to that of fuel storage chamber 51, is smaller in volume than the fuel storage chamber 52 so that a small volume of fuel under pressure in the actuating chamber 55 can be used to effect the pumping of a larger volume of fuel in fuel storage chamber 52 back to the fuel bowl. Continued operation of the fuel pump 12 will then pressurize the fuel in conduit 21 sufficiently to open the flow control valve 22 and allow normal delivery of fuel from the fuel pump to the float bowl 23 as determined by the float and needle valve assembly in the carburetor float bowl.

Using only fuel in the system disclosed instead of fuel and oil as in previously suggested systems, there is no possibility of contamination of the fuel with oil in case of diaphragm failure.

What is claimed is:

1. A fuel evaporative loss control system for use with an internal combustion engine including a fuel tank, a fuel induction system for the engine having a vented induction system fuel reservoir means, a fuel pump having a pumping chamber in communication with an inlet valve and a discharge valve, each having bleed orifices therein, first conduit means connecting said pumping chamber via said inlet valve to said fuel tank, second conduit means connecting said pumping chamber via said discharge valve to said vented induction system fuel reservoir, an accumulator having a variablevolume fuel reservoir with a first movable wall means and an actuating chamber with a second movable wall means and an actuating chamber with a second movable wall means with means connecting said first movable wall means to said second movable wall means and spring means positioned to normally bias said first movable wall means in a direction to enlarge said variable-volume fuel reservoir, and return conduit means connecting said vented induction system fuel reservoir means to said variable-volume fuel reservoir, said second conduit means connecting said pumping chamber via said discharge valve to said actuating chamber.

2. A fuel evaporative loss control system according to claim 1 wherein said return conduit means includes valve means to control the flow of fuel from said variable volume fuel reservoir to said vented induction system fuel reservoir means.

3. A fuel evaporative loss control system according to claim 2 wherein said valve means includes a flow valve assembly having a valve normally seated to close communication from said variable volume fuel reservoir to said vented induction system fuel reservoir means, fuel pressure actuated means positioned to effect unseating of said valve, and means connecting said fuel pressure actuated means to said pumping chamber via said discharge valve.

4. A fuel evaporative loss control system for use with an internal combustion engine including a fuel tank, a fuel induction system for the engine having a vented carburetor fuel bowl, a fuel pump having a pumping chamber with a bleed valve inlet and a bleed valve discharge, first conduit means connecting said bleed valve inlet of said pumping chamber to said fuel tank, second conduit means connecting said bleed valve discharge of said pumping chamber to said carburetor fuel bowl, a variable-volume fuel reservoir means with a first movable wall means, an actuating chamber means with a second movable wall means, said first movable wall means being connected for movement with said second movable wall means, spring means normally biasing said first movable wall means in a direction to enlarge said variable-volume fuel reservoir means, and return conduit means connecting said vented carburetor fuel bowl to said variable-volume fuel reservoir means, said second conduit means connecting said bleed valve discharge of said pumping chamber to said actuating chamber means.

5. A fuel evaporative loss control system according to claim 4 wherein said return conduit means includes valve means having a flow valve assembly with a valve normally seated to close communication between said variable-volume fuel reservoir means and said carburetor fuel bowl, fuel pressure actuated means positioned to effect unseating of said valve, and means connecting said fuel pressure actuated means to said bleed valve discharge of said pumping chamber.

6. An accumulator for use in the fuel system of an internal combustion engine having a carburetor float bowl and a fuel supply system including a fuel pump with a bleed type inlet valve and discharge valve, said accumulator including a housing having means defining a variable-volume storage chamber with a movable wall, an inversely variable-volume actuating chamber with a wall movable with said movable wall, spring means to bias said movable wall in one direction to enlarge said variable-volume storage chamber, diaphragm means defining with said housing a first control chamber on one side of said diaphragm and a second control chamber on the other side of said diaphragm, normally closed valve means positioned to connect said second control chamber to said variable-volume storage chamber, and means connected to said diaphragm for movement therewith and positioned to open said normally closed valve means, said second control chamber being connectable to said fuel bowl for draining fuel therefrom to said variable-volume storage chamber, said actuating chamber and said first control chamber being connectable to the discharge valve of said fuel pump.

7. An accumulator for use in the fuel system of an internal combustion engine havin a fuel supply system includin a carburetor float bowl and fuel pump means for delivering 5161 to the carburetor float bowl from a fuel tank, said accumulator including a housing having means defining a variable-displacement fuel storage chamber with a movable wall means, spring means positioned to normally bias said movable wall in a first direction to enlarge said fuel storage chamber, an actuating means operatively connected to said movable wall means for moving it in a direction opposite to said first direction, normally closed valve means positioned to control the ingress and egress of fuel to said fuel storage chamber and connectable with said carburetor float bowl, and second actuating means positioned to actuate said valve means, said actuating means and said second actuating means being connectable to the discharge side of the fuel pump means.

8. In combination with an internal combustion engine, a fuel delivery and fuel evaporative loss control system comprising a remote fuel tank, a fuel induction means including an induction fuel reservoir for the engine, fuel pump means for delivering fuel from said fuel tank to said induction fuel reservoir during engine operation, and accumulator means having a variable-volume fuel storage chamber means connected to said induction fuel reservoir for draining fuel therefrom and storing it in said variable-volume fuel storage chamber when the engine is not in operation and having an actuating chamber operatively connected to said variable-volume fuel storage chamber means and to said fuel pump means whereby fuel stored in said variable-volume fuel storage means when the engine is not in operation is pumped back to said induction fuel reservoir immediately upon engine operation. 

1. A fuel evaporative loss control system for use with an internal combustion engine including a fuel tank, a fuel induction system for the engine having a vented induction system fuel reservoir means, a fuel pump having a pumping chamber in communication with an inlet valve and a discharge valve, each having bleed orifices therein, first conduit means connecting said pumping chamber via said inlet valve to said fuel tank, second conduit means connecting said pumping chamber via said discharge valve to said vented induction system fuel reservoir, an accumulator having a variable-volume fuel reservoir with a first movable wall means and an actuating chamber with a second movable wall means and an actuating chamber with a second movable wall means with means connecting said first movable wall means to said second movable wall means and spring means positioned to normally bias said first movable wall means in a direction to enlarge said variable-volume fuel reservoir, and return conduit means connecting said vented induction system fuel reservoir means to said variable-volume fuel reservoir, said second conduit means connecting said pumping chamber via said discharge valve to said actuating chamber.
 2. A fuel evaporative loss control system according to claim 1 wherein said return conduit means includes valve means to control the flow of fuel from said variable volume fuel reservoir to said vented induction system fuel reservoir means.
 3. A fuel evaporative loss control system according to claim 2 wherein said valve means includes a flow valve assembly having a valve normally seated to close communication from said variable volume fuel reservoir to said vented induction system fuel reservoir means, fuel pressure actuated means positioned to effect unseating of said valve, and means connecting said fuel pressure actuated means to said pumping chamber via said discharge valve.
 4. A fuel evaporative loss control system for use with an internal combustion engine including a fuel tank, a fuel induction system for the engine having a vented carburetor fuel bowl, a fuel pump having a pumping chamber with a bleed valve inlet and a bleed valve discharge, first conduit means connecting said bleed valve inlet of said pumping chamber to said fuel tank, second conduit means connecting said bleed valve discharge of said pumping chamber to said carburetor fuel bowl, a variable-volume fuel reservoir means with a first movable wall means, an actuating chamber means with a second movable wall means, said first movable wall means being connected for movement with said second movable wall means, spring means normally biasing said first movable wall means in a direction to enlarge said variable-volume fuel reservoir means, and return conduit means connecting said vented carburetor fuel bowl to said variable-volume fuel reservoir means, said second conduit means connecting said bleed valve discharge of said pumping chamBer to said actuating chamber means.
 5. A fuel evaporative loss control system according to claim 4 wherein said return conduit means includes valve means having a flow valve assembly with a valve normally seated to close communication between said variable-volume fuel reservoir means and said carburetor fuel bowl, fuel pressure actuated means positioned to effect unseating of said valve, and means connecting said fuel pressure actuated means to said bleed valve discharge of said pumping chamber.
 6. An accumulator for use in the fuel system of an internal combustion engine having a carburetor float bowl and a fuel supply system including a fuel pump with a bleed type inlet valve and discharge valve, said accumulator including a housing having means defining a variable-volume storage chamber with a movable wall, an inversely variable-volume actuating chamber with a wall movable with said movable wall, spring means to bias said movable wall in one direction to enlarge said variable-volume storage chamber, diaphragm means defining with said housing a first control chamber on one side of said diaphragm and a second control chamber on the other side of said diaphragm, normally closed valve means positioned to connect said second control chamber to said variable-volume storage chamber, and means connected to said diaphragm for movement therewith and positioned to open said normally closed valve means, said second control chamber being connectable to said fuel bowl for draining fuel therefrom to said variable-volume storage chamber, said actuating chamber and said first control chamber being connectable to the discharge valve of said fuel pump.
 7. An accumulator for use in the fuel system of an internal combustion engine having a fuel supply system including a carburetor float bowl and fuel pump means for delivering fuel to the carburetor float bowl from a fuel tank, said accumulator including a housing having means defining a variable-displacement fuel storage chamber with a movable wall means, spring means positioned to normally bias said movable wall in a first direction to enlarge said fuel storage chamber, an actuating means operatively connected to said movable wall means for moving it in a direction opposite to said first direction, normally closed valve means positioned to control the ingress and egress of fuel to said fuel storage chamber and connectable with said carburetor float bowl, and second actuating means positioned to actuate said valve means, said actuating means and said second actuating means being connectable to the discharge side of the fuel pump means.
 8. In combination with an internal combustion engine, a fuel delivery and fuel evaporative loss control system comprising a remote fuel tank, a fuel induction means including an induction fuel reservoir for the engine, fuel pump means for delivering fuel from said fuel tank to said induction fuel reservoir during engine operation, and accumulator means having a variable-volume fuel storage chamber means connected to said induction fuel reservoir for draining fuel therefrom and storing it in said variable-volume fuel storage chamber when the engine is not in operation and having an actuating chamber operatively connected to said variable-volume fuel storage chamber means and to said fuel pump means whereby fuel stored in said variable-volume fuel storage means when the engine is not in operation is pumped back to said induction fuel reservoir immediately upon engine operation. 